U.S. patent application number 09/883372 was filed with the patent office on 2002-03-14 for driving belt and transverse element for a driving belt.
This patent application is currently assigned to Van Doorne's Transmissie b.v.. Invention is credited to Van Liempd, Jeroen Herman, Van Lith, Johannes Hendrikus, Van Schaik, Marco.
Application Number | 20020032090 09/883372 |
Document ID | / |
Family ID | 19771573 |
Filed Date | 2002-03-14 |
United States Patent
Application |
20020032090 |
Kind Code |
A1 |
Van Lith, Johannes Hendrikus ;
et al. |
March 14, 2002 |
Driving belt and transverse element for a driving belt
Abstract
A driving belt for use in a continuously variable transmission
comprising two V-shaped pulleys. The driving belt comprises a
carrier consisting of two endless band packages lying side by side,
on which transverse elements are disposed. Each transverse element
includes two recesses positioned opposite each other for receiving
the band packages, so that a part of the transverse element is
positioned between said band packages. Each recess includes an
inside surface facing towards the band package, wherein the portion
of the inside surface that is formed by the aforesaid part of the
transverse element includes an acute angle, near the underside of
the band packages, with the plane in which the band packages
lie.
Inventors: |
Van Lith, Johannes Hendrikus;
(Berlicum, NL) ; Van Liempd, Jeroen Herman;
(Bavel, NL) ; Van Schaik, Marco; (Berda,
NL) |
Correspondence
Address: |
YOUNG & THOMPSON
745 SOUTH 23RD STREET 2ND FLOOR
ARLINGTON
VA
22202
|
Assignee: |
Van Doorne's Transmissie
b.v.,
|
Family ID: |
19771573 |
Appl. No.: |
09/883372 |
Filed: |
June 19, 2001 |
Current U.S.
Class: |
474/242 |
Current CPC
Class: |
F16G 5/16 20130101 |
Class at
Publication: |
474/242 |
International
Class: |
F16G 001/21; F16G
005/16; F16G 001/22 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 2000 |
EP |
1015491 |
Claims
1. A driving belt for use in a continuously variable transmission
comprising two V-shaped pulleys (2, 3), which driving belt (1)
comprises a carrier consisting of two endless band packages (5, 6)
lying side by side, on which transverse elements (4) are disposed,
wherein each transverse element (4) includes two recesses (7, 8)
positioned opposite each other for receiving the band packages (5,
6), so that a first part (11) of the transverse element (4) extends
under said band packages (5, 6), a second part (12) of the
transverse element (4) is positioned between said band packages (5,
6) and a third part (13) of the transverse element (4) extends
above said band packages (5, 6), wherein each recess includes an
inside surface (21, 22, 23) facing towards the band package (5, 6),
characterised in that the portion (22) of the inside surface that
is formed by said second part (12) of the transverse element (4)
includes an acute angle (a), near the underside of the band
packages (5, 6), with the plane in which the band packages (5, 6)
lie.
2. A driving belt according to claim 1, characterised in that said
angle (a) is less than 85.degree., preferably less than 75.degree.,
more preferably less than 60.
3. A driving belt according to any one of the preceding claims,
characterised in that the portion (22) of the inside surface that
is formed by the second part (12) of the transverse element (4)
includes a substantially flat part, whose length (height) is
smaller than the thickness (W) of a band package.
4. A driving belt according to any one of the preceding claims,
characterised in that the portion (22) of the inside surface that
is formed by said second part (12) of the transverse element (4)
exhibits a concave curvature over its entire area.
5. A driving belt according to any one of the preceding claims,
characterised in that the radius of curvature (R1) of the concave
portion of the inside surface (21, 22) at the transition between
said first part (11) and said second part (12) of the transverse
element (4) is more than one third, preferably more than half, of
the smallest distance (A) between the portion (21) of the inside
surface that is formed by the first part (11) of the transverse
element (4) and the portion (23) of the inside surface that is
formed by the third part (13) of the transverse element (4).
6. A driving belt according to any one of the preceding claims,
characterised in that the radius (R1) of the concave curvature of
the inside surface (21, 22) at the transition between said first
part (11) and said second part (12) of the transverse element (4)
is more than 0.7 mm, preferably more than 0.9 mm.
7. A driving belt according to claim 6, characterised in that said
convex curvature has a radius (R2) of more than 0.6 mm, preferably
more than 1.5 mm, more preferably more than 2 mm.
8. A driving belt according to any one of the preceding claims,
characterised in that the smallest vertical distance (A) of the
recess amounts to more than 75% of the largest vertical distance
(B) of the recess near the second part (12) of the transverse
element (4), preferably more than 85%.
9. A driving belt according to any one of the preceding claims,
characterised in that the width (W) of a band package (5, 6) is
more than 80%, preferably more than 90%, of the largest distance
between the surface (25) of the transverse element (4) that can
come into contact with the pulley (2, 3) and the second part (12)
of the transverse element (4).
10. A driving belt according to any one of the preceding claims,
characterised in that the transverse element (4) has been made from
a strip of material by means of a cutting operation or by means of
a material-deforming operation.
11. A driving belt according to any one of the preceding claims,
characterised in that edges of the transverse element (4) have been
deburred and/or been rounded by means of a tumbling operation.
12. A transverse element for use in a driving belt (1) for a
continuously variable transmission comprising two V-shaped pulleys
(2, 3), in particular as defined in any one of the preceding
claims, which transverse element (4) includes two recesses (7, 8)
positioned opposite each other for receiving the band packages (5,
6), so that a first part (11) of the transverse element (4) extends
under said band packages (5, 6), a second part (12) of the
transverse element (4) is positioned between said band packages (5,
6) and a third part (13) of the transverse element (4) extends
above said band packages (5, 6), wherein each recess (7, 8)
includes an inside surface (21, 22, 23) facing towards the band
package (5, 6), characterised in that the portion (22) of the
inside surface that is formed by said second part (12) of the
transverse element (4) includes an acute angle (a), near the
underside of the band packages (5, 6), with the plane in which the
band packages (5, 6) lie.
Description
[0001] The invention relates to a driving belt for use in a
continuously variable transmission comprising two V-shaped pulleys,
which driving belt comprises a carrier consisting of two endless
band packages lying side by side, on which transverse elements are
disposed, wherein each transverse element includes two recesses
positioned opposite each other for receiving the band packages, so
that a first part of the transverse element extends under said band
packages, a second part of the transverse element is positioned
between said band packages and a third part of the transverse
element extends above said band packages, wherein each recess
includes an inside surface facing towards the band package. Such a
driving belt is known from EP-A-0 014 013.
[0002] In practice it has become apparent that the shape of the
inside surface of the recess must meet specific requirements in
order to effect a satisfactory operation of the driving belt. Said
shape in particular has an influence on the correct operation of
the band packages, which form vulnerable parts of the driving belt.
They are subjected to a relatively large tensile strain, and also
to a substantial, varying flexural strain, which depends on the
transmission ratio that has been selected. Said band packages make
contact with the aforesaid inside surface, whereby they can also
make contact with the inside surface at the location of the
aforesaid second part of the transverse element. It is especially
for that reason that in practice said inside surface is always a
flat surface, which extends in vertical longitudinal direction.
[0003] Each time a direction is described in relation to a
transverse element, it is assumed that the transverse element
occupies an upright position, as is shown in front elevation in
FIG. 2. In said figure, the longitudinal direction is the direction
perpendicularly to the plane of the figure.
[0004] It has become apparent upon testing the strength of the
transverse element that the use of relatively small radii has a
relatively large negative influence on the strength of the
transverse element. The strength of the transverse element
furthermore appears to be critical near the aforesaid second part
of the transverse element.
[0005] The object of the invention is to improve with regard to the
shape of the transverse element, which benefits the strength of
said transverse element.
[0006] According to the invention, in order to accomplish that
objective, the portion of the inside surface that is formed by said
second part of the transverse element includes an acute angle (a),
near the underside of the band packages, with the plane in which
the band packages lie.
[0007] In particular when measures are taken to retain the band
packages correctly in position during operation of the driving
belt, any contact that may take place especially between in
particular the lowermost band of a band package and the inside
surface at the location of the second part of the transverse
element appears to involve little force, so that the risk of damage
is small. The band packages can be retained in position, in
particular during operation, in that the inside surface is designed
to be slightly convex at the location of said first part of the
transverse element.
[0008] By designing the flat part of the inside surface with a
smaller surface area at the location of the second part of the
transverse element, which is the object of the aforesaid measure,
or even forming the relevant part of the inside surface with a
curvature in its entirety, larger radii can be used for the
rounding of the inside surface near the second part of the
transverse element.
[0009] Preferably, said angle (a) is less than 85.degree., more
preferably less than 75.degree. and even more preferably less than
60.degree.. Also an angle (a) of less than 45.degree. can be used
advantageously.
[0010] In one preferred embodiment, the portion of the inside
surface that is formed by the second part of the transverse element
includes a substantially flat part, whose length (height) is
smaller than the thickness of a band package. Furthermore, the
portion of the inside surface that is formed by said second part of
the transverse element may exhibit a concave curvature over its
entire area.
[0011] Preferably, the radius of curvature of the concave portion
of the inside surface at the transition between said first and said
second part of the transverse element is more than one third,
preferably more than half, of the smallest distance between the
portion of the inside surface that is formed by the first part of
the transverse element and the portion of the inside surface that
is formed by the third part of the transverse element.
[0012] In one preferred embodiment the radius (R1) of the concave
curvature of the inside surface at the transition between said
first part and said second part of the transverse element is more
than 0.7 mm, preferably more than 0.9 mm.
[0013] In one preferred embodiment the portion of the inside
surface that is formed by the first part of the transverse element
exhibits a convex curvature having a radius (R2) of more than 0.6
mm, preferably more than 1.5 mm, more preferably more than 2 mm,
near the transition to the portion of the inside surface that is
formed by the second part of the transverse element. A larger
radius has a positive effect on the life of the band packages.
[0014] Preferably, the smallest vertical distance (A) of the recess
amounts to more than 75% of the largest vertical distance (B) of
the recess near the second part of the transverse element, more
preferably more than 85%.
[0015] In one preferred embodiment the width of a band package is
more than 80%, preferably more than 90%, of the largest distance
between the surface of the transverse element that can come into
contact with the pulley and the second part of the transverse
element.
[0016] Preferably, the transverse element is made from a strip of
material by means of a cutting operation, and the edges of the
transverse element have been deburred and/or been rounded by means
of a tumbling operation.
[0017] The invention furthermore relates to a transverse element
for use in a driving belt for a continuously variable transmission
comprising two V-shaped pulleys, which transverse element includes
two recesses positioned opposite each other for receiving band
packages forming a carrier, so that a first part of the transverse
element extends under said band packages, a second part of the
transverse element is positioned between said band packages and a
third part of the transverse element extends above said band
packages, wherein each recess includes an inside surface facing
towards the band package, wherein the portion of the inside surface
that is formed by said second part of the transverse element
includes an acute angle (a), near the underside of the band
packages, with the plane in which the band packages lie.
[0018] In order to explain the invention more fully, an exemplary
embodiment of a driving belt will be described hereafter with
reference to the drawing.
[0019] FIG. 1 is a schematic side view of a driving belt;
[0020] FIG. 2 is a front view of a transverse element;
[0021] FIG. 3 is a side view of the transverse element;
[0022] FIG. 4 is a rear view of the transverse element; and
[0023] FIG. 5 is a view of a detail of FIG. 4.
[0024] The schematic illustration of FIG. 1 shows the driving belt
1, which runs over two pulleys 2, 3. In the illustrated situation,
the left-hand pulley 2 rotates faster than the right-hand pulley 3.
By changing the mutual distance between the two parts of which each
pulley 2, 3 consists, it is possible to change the radius of the
driving belt 1 at the location of pulley 2, 3, as a result of which
the difference in speed between the two pulleys 2, 3 can be varied
as desired. This is a well-known way of varying a difference in
rotational speed between two shafts.
[0025] The driving belt 1, which is shown in side elevation in FIG.
1, is built up of a plurality of transverse elements 4 (four of
which are shown in FIG. 1) and two band packages 5, 6, one of which
is indicated by the shaded part in the figure. Both the transverse
elements 4 and the bands of the band packages 5, 6 are made of a
metal. The transverse elements 4 can move freely in the
longitudinal direction of the band packages 5, 6, so that when a
force is being transmitted between pulleys 2, 3, said force is
transmitted by the transverse elements 4 pressing one against
another. The band packages guide the transverse elements 4
thereby.
[0026] In the illustrated embodiment, each band package 5, 6
consists of five bands, as is shown in FIG. 2. In practice, a band
package 5, 6 frequently comprises more bands, for example ten. In
FIG. 2, the thickness of the band package 6 is indicated at T and
the width is indicated at W. The thickness of a band is 0.2 mm, for
example, with the width being 7 mm.
[0027] It will be apparent that the band packages 5, 6 cannot move
out laterally, because parts of the pulleys 2, 3 are positioned on
either side of the driving belt 1. From the figures it is apparent
that the shape of transverse elements 4 has been selected so that
said transverse elements are retained in position by the band
packages 5, 6. Said shape comprises two recesses 7, 8, in which the
band packages 5, 6 are accommodated.
[0028] Transverse element 4 consists of a first part 11, which
extends under band packages 5, 6, a second part 12, which is
located under band packages 5, 6, and a third part 13, which
extends above band packages 5, 6.
[0029] The rear side of transverse element 4 (shown in FIG. 4) is
substantially flat, and on its front side (shown in FIG. 2),
transverse element 4 exhibits a so-called tilting line 18. The part
of transverse element 4 above tilting line 18 has a substantially
constant thickness, seen in side elevation (FIG. 3), whilst the
first part 11 under tilting line 18 tapers off in downward
direction. Tilting line 18 is in fact formed by a slightly rounded
strip on the front side of transverse element 4, for example by an
edge having a radius of curvature of 6 mm. Tilting line 18 is in
contact with the rear side of the adjacent transverse element 4,
both in the straight parts of driving belt 1 and in the curved
parts thereof.
[0030] Below tilting line 18, first part 11 tapers off to an edge
26 extending in horizontal direction. First part 11 below edge 26
exhibits a constant thickness, which is about 0.1 mm less than the
thickness of transverse element 4 just above edge 26.
[0031] As can be seen in particular in FIG. 3, the second part 12
of transverse element 4 is shifted to the left (in FIG. 3), as a
result of which a projection 14 is formed on the front side of
transverse element 4, whilst a recess 15 is present on the rear
side. As is apparent from FIGS. 2 and 4, projection 14 and recess
15 extend in horizontal direction over the entire second part 12 of
transverse element 4.
[0032] Projection 14 and recess 15 interlock in the straight parts
of driving belt 1, as a result of which two abutting transverse
elements 4 are prevented from shifting relative to each other.
[0033] As FIG. 2 shows, projection 14 is centrally provided with a
recessed part 16, and FIG. 4 shows that recess 15 is centrally
provided with a projecting part 17. In this manner, the surfaces of
projection 14 and recess 15 include parts which extend at an angle
to a horizontal line in the plane in which band packages 5, 6 lie,
and which extends perpendicularly to the direction of driving belt
1.
[0034] In a straight part of the driving belt 1, the projecting
part 17 comes into engagement with the recessed part 16, so that
relative movement of two transverse elements 4 lying adjacently to
each other is reduced or prevented altogether as a result of said
parts including an angle coming into contact with each other.
[0035] As appears from the figures, projection 14 and recess 15 are
located entirely in the second part 12 of transverse element 4, as
a result of which their dimension in transverse direction
(horizontal direction) is limited.
[0036] Each of the recesses 7, 8 is bounded by an inside surface
that is formed by portions of first part 11, second part 12 and
third part 13 of transverse element 4. Said portions are indicated
by numerals 21, 22 and 23, respectively, in FIG. 5.
[0037] FIG. 5 is a detailed view of the shape of recess 7. Inside
surface 21 includes a straight or slightly curved part at the
location of first part 11 of transverse element 4, which part comes
into contact with the band package 5. Said part merges with a
convex portion thereof having a radius R2 into a concave portion of
the inside surface having a radius R1 at the location where portion
21 of the inside surface merges with portion 22.
[0038] In the illustrated embodiment, R1 equals approximately half
the distance B, which distance is the largest vertical dimension of
recess 7 near the second part 12 of transverse element 4. The
inside surface 22 at the location of second part 12 may exhibit a
vertical, straight portion at the location of second part 12, but
in the present embodiment said portion 22 of the inside surface is
curved in its entirety, and that practically in the form of an arc
having a radius R1.
[0039] In FIG. 5, letter A indicates the smallest vertical
dimension of recess 7, which dimension is preferably larger than
80% of the largest vertical dimension B of recess 7 near the second
part 12 of transverse element 4.
[0040] FIG. 5 shows angle a, which is the angle which the portion
22 of the inside surface that is formed by the second part 12 of
transverse element 4 includes near the underside of band packages
5, 6 with the plane in which band packages 5, 6 lie. As is shown in
FIG. 5, said angle is an acute angle, preferably of less than
85.degree..
[0041] In practice it has become apparent that the convex curvature
having radius R2 must be sufficiently large, for example 0.4 mm or
more. When the radius R2 is not large enough, damage to the
innermost band of the band package 5, 6 may ensue. Also the radius
R1 of the adjoining concave curvature must be sufficiently large.
It has become apparent that when R1 is larger than 0.7 mm, the risk
of fracture of the transverse element 4 is reduced to such an
extent that the first part 11 of 64 may be smaller, that is, have
less mass. It is possible thereby to reduce the distance between
the lower edge 24 of transverse element 4 and the inside surface
21, 22 at the location of the aforesaid curvature significantly,
that is, said distance can be much smaller than the height H of the
surface 25 of transverse element 4 that comes into contact with
pulleys 2, 3. Said reduction contributes to a satisfactory dynamic
behaviour of the transverse element. Preferably, the lower edge 24
is concave over substantially its entire length.
[0042] The above-described embodiment is merely an exemplary
embodiment; many other embodiments are possible.
* * * * *